/Engine/Source/Runtime/Engine/Classes/GameFramework/CharacterMovementComponent.h
Add impulse to character. Impulses are accumulated each tick and applied together so multiple calls to this function will accumulate. An impulse is an instantaneous force, usually applied once. If you want to continually apply forces each frame, useAddForce(). Note that changing the momentum of characters like this can change the movement mode.
virtual void AddImpulse ( FVector Impulse, bool bVelocityChange )